We speak of the wisdom of the serpent; but it is not very easy to
justify the phrase. Among all the multitude of reptiles--snakes,
lizards, turtles, and crocodiles, a motley crowd--we cannot see much
more than occasional traces of intelligence. The inner life remains a
tiny rill.
No doubt many reptiles are very effective; but it is an instinctive
rather than an intelligent efficiency. The well-known "soft-shell"
tortoise of the United States swims with powerful strokes and runs so
quickly that it can hardly be overtaken. It hunts vigorously for
crayfish and insect larvæ in the rivers. It buries itself in the mud
when cold weather comes. It may lie on a floating log ready to slip into
the water at a moment's notice; it may bask on a sunny bank or in the
warm shallows. Great wariness is shown in choosing times and places for
egg-laying. The mother tramps the earth down upon the buried eggs. All
is effective. Similar statements might be made in regard to scores of
other reptiles; but what we see is almost wholly of the nature of
instinctive routine, and we get little glimpse of more than efficiency
and endeavour.
In a few cases there is proof of reptiles finding their way back to
their homes from a considerable distance, and recognition of persons is
indubitable. Gilbert White remarks of his tortoise: "Whenever the good
old lady came in sight who had waited on it for more than thirty years,
it always hobbled with awkward alacrity towards its benefactress, while
to strangers it was altogether inattentive." Of definite learning there
are a few records. Thus Professor Yerkes studied a sluggish turtle of
retiring disposition, taking advantage of its strong desire to efface
itself. On the path of the darkened nest of damp grass he interposed a
simple maze in the form of a partitioned box. After wandering about
constantly for thirty-five minutes the turtle found its way through the
maze by chance. Two hours afterwards it reached the nest in fifteen
minutes; and after another interval of two hours it only required five
minutes. After the third trial, the routes became more direct, there was
less aimless wandering. The time of the twentieth trial was forty-five
seconds; that of the thirtieth, forty seconds. In the thirtieth case,
the path followed was quite direct, and so it was on the fiftieth trip,
which only required thirty-five seconds. Of course, the whole thing did
not amount to very much; but there was a definite learning, _a learning
from experience_, which has played an important part in the evolution of
animal behaviour.
Comparing reptiles with amphibians, we may recognise an increased
masterliness of behaviour and a hint of greater plasticity. The records
of observers who have made pets of reptiles suggest that the life of
feeling or emotion is growing stronger, and so do stories, if they can
be accepted, which suggest the beginning of conjugal affection.
The error must be guarded against of interpreting in terms of
intelligence what is merely the outcome of long-continued structure
adaptation. When the limbless lizard called the Slow-worm is suddenly
seized by the tail, it escapes by surrendering the appendage, which
breaks across a preformed weak plane. But this is a reflex action, not a
reflective one. It is comparable to our sudden withdrawal of our finger
from a very hot cinder. The Egg-eating African snake Dasypeltis gets the
egg of a bird into its gullet unbroken, and cuts the shell against
downward-projecting sharp points of the vertebræ. None of the precious
contents is lost and the broken "empties" are returned. It is admirable,
indeed unsurpassable; but it is not intelligent.
§ 5